The invention relates to a device for sterilizing water flowing through a sanitary appliance, having
a) a housing, which comprises an inlet and an outlet for the water;
b) a UV lamp, which is disposed inside the housing and the radiation of which is directed towards the water flowing through; and
c) a throughflow chamber for the water, which is disposed in the housing and surrounds the UV lamp.
In recent years the dangers arising in the field of sanitation from water contaminated with micro-organisms, in particular bacteria, amoebae or other monocellular organisms, have become ever clearer. For said reason, increased importance is being attached to water sterilization. In said connection, there have been reports of experiments to sterilize flowing water through exposure to UV light, which is of a wavelength suitable for killing micro-organisms carried along in the water. In said case, the water to be sterilized flows around the UV lamp.
It is known that the sterilizing effect of such a UV lamp is dependent upon parameters such as the radiation capacity and the radiated wavelength spectrum of the lamp and that said parameters in turn are dependent upon the operating temperature of the lamp body of the UV lamp. In known devices, the high thermal contact with the water flowing around the lamp influences the temperature of the lamp body. The extent of said influence depends upon the temperature of the water and the flow rate of the water. Different water removal conditions, such as e.g. a different water temperature or different levels of water removal, lead to correspondingly different operating temperatures of the lamp body.
Changes of the operating parameters of the lamp body which lead to a reduction of the sterilizing efficiency arise as a result. In order nevertheless always to achieve an adequate sterilizing effect, the UV lamps of such known devices are required, for safety reasons, to be overrated in terms of their capacity, which has a corresponding disadvantageous effect upon the cost of constructing and operating the device. An additional drawback arises when, as a result of the absorption of the overrated radiant power of the UV lamp, the sterilizing device heats up in a way that makes it difficult to handle or reduces its operational reliability.
The object of the present invention is therefore to develop a device of the type described initially in such a way that the efficiency of the UV lamp is not influenced by different water removal conditions.
Said object is achieved according to the invention in that
d) the lamp comprises a substantially rod-shaped lamp body;
e) the lamp body is surrounded by a protective tube, which is made substantially of a UV-light-transmitting material and prevents a flow directly against the lamp body; and that
f) the lamp body is supported against the protective tube by means of supporting means, which allow only a low heat transfer between the protective tube and the lamp body.
A substantially rod-shaped lamp body has a relatively large lateral surface, past which the water to be sterilized flows. The water, as it flows past from the upstream to the downstream end of the throughflow chamber, is continuously exposed to irradiation by the UV lamp and may therefore be effectively sterilized. In so doing, it does not flow directly in contact with the lamp body but is separated from the latter by a protective tube, which transmits UV light.
Said protective tube is used to isolate the sensitive lamp body from direct contact with the water. By virtue of the supporting means, which support the lamp body relative to the protective tube and form only a slight thermal bridge between the lamp body and the protective tube, the temperature of the lamp body is practically uninfluenced by the temperature of the protective tube, which is determined by the heat exchange with the water flowing past. It is therefore possible under all water removal conditions for the lamp to be kept at an optimum operating temperature, at which it has the best sterilizing effect.
In an advantageous refinement of the invention, the supporting means are supported against an inner lateral surface of the protective tube. Such an arrangement for supporting the lamp body inside the protective tube is simple and places no high demands on the shaping of the supporting means.
Advantageously, the supporting means are applied only via edges against the inner lateral surface of the protective tube. As a result, the region contributing towards heat transfer is reduced compared to a surface-type support.
In a particularly advantageous manner, the supporting means are applied only via tips against the inner lateral surface of the protective tube. This leads to an even greater reduction of the region which may contribute towards heat transfer.
In an advantageous embodiment of the present invention, the supporting means, viewed in the direction of the lamp axis, have the external contour of a polygon. Such supporting means have an uncomplicated geometry and are accordingly inexpensive to manufacture.
In a particularly advantageous construction, the polygon is a triangle. A triangle has the minimum number of outside edges enabling a stable support of the lamp body against the inner lateral surface of the protective tube.
In a further advantageous refinement of the invention, a resilient connection is formed by at least one of the supporting means between the lamp body and the protective tube. Such a resilient connection may absorb thermal stresses which arise during operation of the UV lamp. It moreover protects the lamp body from damage caused by vibrations which may be generated e.g. by the water flowing past or by operation of the UV lamp itself.
The supporting means advantageously support the lamp body at both ends. A stable and secure mounting of the lamp body is thereby guaranteed.
In a further advantageous refinement of the invention, the lamp body comprises projections protruding from either end and the supporting means are mounted, at the lamp body side, on the protruding projections. Such projections may, for example, be conditional upon the method of manufacturing the lamp. The mounting on said projections dispenses with the need to provide receiving devices for the supporting means on the lamp body in a separate step.
The projections are advantageously electrical connection means of the UV lamp. Besides receiving the supporting means, projections designed in said manner additionally perform the function of electrical contacting of the UV lamp.